The present disclosure relates to a power transmission device, and more in detail, to a power transmission device that is mounted on a vehicle and that includes a transmission including a plurality of engagement elements for transmitting power from a motor to axles, a case for accommodating the transmission, and a hydraulic control device for controlling hydraulic pressure to the engagement elements.
Power transmission devices of such a type have heretofore been proposed, each of which is mounted on a vehicle and includes an automatic transmission including a plurality of clutches, a hydraulic circuit serving as an actuator for driving the clutches, a mechanical oil pump that is driven by power from an engine to suction hydraulic oil from an oil pan via a strainer and supply the hydraulic oil to the hydraulic circuit, and an electromagnetic pump that is driven by an electromagnetic force to be capable of suctioning the hydraulic oil from an oil passage between the strainer and the mechanical oil pump and supplying the hydraulic oil to a clutch for starting the vehicle (refer to Japanese Patent Application Publication No. 2010-164178, for example). In this device, while the engine is automatically stopped, a hydraulic pressure is applied to the clutch for starting the vehicle from the electromagnetic pump instead of a linear solenoid valve of the hydraulic circuit, so that the linear solenoid valve can quickly engage the clutch immediately after the engine is automatically started next time, thereby starting the vehicle smoothly.
In such a power transmission device, in some cases depending on the way of arranging the electromagnetic pump, a communication oil passage for communicating the oil passage between the strainer and the mechanical oil pump with a suction port of the electromagnetic pump increases in length. The increase in length of the communication oil passage increases the suction resistance of the electromagnetic pump, causing difficulty in applying sufficient hydraulic pressure to the clutch for starting the vehicle from the electromagnetic pump.
The present disclosure according to an exemplary aspect provides a power transmission device that is capable of applying sufficient hydraulic pressure from a pump operated by receiving supply of electric power to an engagement element for starting the vehicle.
A first power transmission device according to an exemplary aspect of the present disclosure is a power transmission device that is mounted on a vehicle, the power transmission device includes a transmission including a plurality of engagement elements for transmitting power from a motor to axles; a case to accommodate the transmission; a hydraulic control device to control hydraulic pressure to the engagement elements; a hydraulic oil reservoir that stores hydraulic oil; and a first pump that is operated by the power from the motor and that suctions the hydraulic oil from the hydraulic oil reservoir through a strainer and supplies the hydraulic oil to the hydraulic control device, wherein the hydraulic control device includes: a second pump that is operated by receiving supply of electric power and that suctions the hydraulic oil and supplies the hydraulic oil to a starting engagement element among the engagement elements that is engaged to start the vehicle; a discharge port that discharges the hydraulic oil from the first pump; a mounting port for the strainer that communicates with the first pump and to which the strainer is mounted; a first oil passage that communicates the mounting port for the strainer with the first pump; and a second oil passage that communicates the first oil passage with the second pump, and also in that an input/output port group composed of a suction port of the second pump, the mounting port for the strainer, and the discharge port, which are arranged side by side in this order.
In the first power transmission device of the present disclosure, the hydraulic control device includes: the second pump that is operated by receiving the supply of the electric power and that suctions the hydraulic oil and supplies the hydraulic oil to the starting engagement element among the engagement elements that is engaged to start the vehicle; the discharge port that discharges the hydraulic oil from the first pump; the mounting port for the strainer that communicates with the first pump and to which the strainer is mounted; the first oil passage that communicates the mounting port for the strainer with the first pump; and the second oil passage that communicates the first oil passage with the second pump. The input/output port group composed of the suction port of the second pump, the mounting port for the strainer, and the discharge port, which are arranged side by side in this order. This structure allows the second oil passage to be shorter and thus the oil passage resistance (suction resistance of the second pump) to be lower. As a result, sufficient hydraulic pressure can be more easily applied from the second pump to the starting engagement element.
A second power transmission device according to an exemplary aspect of the present disclosure is a power transmission device that is mounted on a vehicle, the power transmission device includes a transmission including a plurality of engagement elements for transmitting power from a motor to axles; a case to accommodate the transmission; a hydraulic control device to control hydraulic pressure to the engagement elements; a hydraulic oil reservoir that stores hydraulic oil; and a first pump that is operated by the power from the motor and that suctions the hydraulic oil from the hydraulic oil reservoir through a strainer and supplies the hydraulic oil to the hydraulic control device, wherein the hydraulic control device includes: a second pump that is operated by receiving supply of electric power and that suctions the hydraulic oil and supplies the hydraulic oil to a starting engagement element among the engagement elements that is engaged to start the vehicle; a discharge port that discharges the hydraulic oil from the first pump; a mounting port for the strainer that communicates with the first pump and to which the strainer is mounted; a first oil passage that communicates the mounting port for the strainer with the first pump; a second oil passage that communicates the first oil passage with the second pump; and a plurality of control valves that control the hydraulic pressure, and also in that: a suction port of the second pump and the mounting port for the strainer are arranged side by side in this order in a direction orthogonal to a direction of mounting the hydraulic control device to a case member of the transmission, and also orthogonal to an axial direction of the transmission; and the suction port of the second pump and the mounting port for the strainer are arranged on a side closer to an internal combustion engine than the control valves are in the axial direction of the transmission.
In the second power transmission device of the present disclosure, the hydraulic control device includes: the second pump that is operated by receiving the supply of the electric power and that suctions the hydraulic oil and supplies the hydraulic oil to the starting engagement element among the engagement elements that is engaged to start the vehicle; the discharge port that discharges the hydraulic oil from the first pump; the mounting port for the strainer that communicates with the first pump and to which the strainer is mounted; the first oil passage that communicates the mounting port for the strainer with the first pump; the second oil passage that communicates the first oil passage with the second pump; and the control valves that control the hydraulic pressure. The suction port of the second pump and the mounting port for the strainer are arranged side by side in this order in the direction orthogonal to the direction of mounting the hydraulic control device to the case member of the transmission, and also orthogonal to the axial direction of the transmission. The suction port of the second pump and the mounting port for the strainer are arranged on a side closer to the internal combustion engine than the control valves are in the axial direction of the transmission. This structure allows the second oil passage to be shorter and thus the oil passage resistance (suction resistance of the second pump) to be lower. As a result, sufficient hydraulic pressure can be more easily applied from the second pump to the starting engagement element.
A third power transmission device according to an exemplary aspect of the present disclosure is a power transmission device that is mounted on a vehicle, the power transmission device includes a transmission including a plurality of engagement elements for transmitting power from a motor to axles; a case to accommodate the transmission; a hydraulic control device to control hydraulic pressure to the engagement elements; a hydraulic oil reservoir that stores hydraulic oil; a first pump that is operated by the power from the motor and that suctions the hydraulic oil from the hydraulic oil reservoir through a strainer and supplies the hydraulic oil to the hydraulic control device; a second pump that is operated by receiving supply of electric power and that suctions the hydraulic oil and supplies the hydraulic oil to a starting engagement element among the engagement elements that is engaged to start the vehicle; a first oil passage that communicates an outlet port of the strainer with the first pump; and a second oil passage that communicates the first oil passage with the second pump, wherein the second pump includes an electromagnetic unit and a pump unit, and is mounted on a valve body of the hydraulic control device such that the pump unit is placed between the electromagnetic unit and the outlet port of the strainer.
The third power transmission device of the present disclosure includes the first oil passage that communicates the outlet port of the strainer with the first pump and the second oil passage that communicates the first oil passage with the second pump. The second pump includes the electromagnetic unit and the pump unit, and is mounted on the valve body of the hydraulic control device such that the pump unit is placed between the electromagnetic unit and the outlet port of the strainer. This structure allows the second oil passage to be shorter and thus the oil passage resistance (suction resistance of the second pump) to be lower than in the case of mounting the second pump on the valve body such that the pump unit is placed farther from the outlet port of the strainer than the electromagnetic unit is. As a result, sufficient hydraulic pressure can be more easily applied from the second pump to the starting engagement element.